This invention relates the controlled opening and closing of tailgates and more particularly to a compact counterbalancing module for controlling the opening and closing of the tailgate.
As will be appreciated, tailgates for pickup trucks typically range in weight from 40 to 70 pounds and are hinged at the rear of the truck bed such that when the tailgate is unlocked by the pulling of a lever or handle, the tailgate opens to a point level with the truck bed where it is restrained usually by detachable folding straps. Typically, the tailgates can be removed from the truck body when the tailgate is pivoted to a partially open tailgate removal position.
The weight of the tailgate precludes one handed operation for any but the strongest individual. People of normal build have to use their second hand, or shoulder or knee to support the tailgate in an effort to kept it from dropping too quickly.
The single-handed supporting of the tailgate often times can result in wrist injury as the weight of the tailgate overpowers the ability of the individual to control its descent and it comes crashing down in an uncontrolled fashion. Normally a person drops the gate or sometimes raises his or her knee in order to arrest the fall of the tailgate.
The raising of one""s knee to prevent the tailgate from dropping has reportedly resulted in crushed knee caps or other damage to the knee, whereas supporting the relatively heavy tailgate through one handed operation has resulted in sprained wrists due to the inability of the individual to hold the heavy tailgate with one hand.
It will be appreciated that a free falling tailgate can, in fact, crush anything that is underneath it and can, for instance, hurt children who are standing at the back of the tailgate when it falls. Moreover, it is hard to close a heavy tailgate.
Note that pickup trucks and vehicles with tailgates are now more popular in suburban settings in which the tailgate is to be lowered, for instance, to load groceries into the back of the pickup. Pickups are also utilized routinely in camping and the provision of camper tops for the pickups has increased their popularity for carrying lighter loads than a pickup is normally designed to carry. This popularity has resulted in the use of these trucks by non-professionals such as family members and indeed anybody associated with the family. Thus, it is important that the tailgate be counterbalanced in such a way that it not cause damage to one trying to lower it and must afford the ability to close the tailgate in a single handed operation easily even by a small person, yet permit rapid removal of the tailgate and the counterbalance mechanism from the truck body.
In the past, tailgates have been counterbalanced by internal torsion bars which are factory installed such as illustrated by U.S. Pat. No. 5,358,301. Since these counterbalancing mechanisms are only installed in a limited number of vehicles, there is a necessity for providing an after-market device to be able to counterbalance the tailgate.
As illustrated by U.S. Pat. No. 5,988,724, issued to Tiete O. Wolda, a torsion bar or torquing device called a torque rod is utilized in the tailgate hinge mechanism such that the tailgate has a torque rod which assists in the opening or closing of the tailgate. While the Wolda patent indicates that his device is suitable for after-market installation, it requires the removal of the hinge bracket, which previously was bolted to the truck""s tailgate. However, presently, the hinge brackets are often spot welded to the tailgate, making after-market utilization impossible.
In an effort to address the after-market, there are those who have tried to use coil springs to counterbalance tailgates. However, coil springs are much too cumbersome and unsightly to be attached to tailgates. One such attempt to use coil springs is illustrated by U.S. Pat. No. 5,954,383, in which a spring-loaded pulley arrangement along with a tether is utilized to assist in the lowering and raising of a tailgate. However, such a lift kit involves the mounting of a channel that houses the pulleys and a sizable spring which obstructs the loading area and is so big that it is difficult to merchandise, for instance on a rack display. Moreover, the device is cumbersome to install and is unsightly.
There is thus a need for an extremely compact easy to attach a counterbalance device that can be hidden from view and yet has the strength to provide the required counterbalance force.
By way of further background, there are a number of devices, which limit the positions of a tailgate, one of which is shown in U.S. Pat. No. 4,585,265. However, there is no counterbalancing action in such a positioning device.
Additionally, there are a number of devices, which are utilized to reduce the aerodynamic drag caused by a tailgate by partially opening it. One such device is illustrated in U.S. Pat. No. 5,645,310, in which a strap keeps the tailgate at a predetermined angle so as to minimize the aerodynamic load. Note that in this device there is no spring loading or any attempt to counterbalance the tailgate.
A further air drag reducing tailgate device is shown in U.S. Pat. No. 5,234,249 issued to Jay I. Durrell in which the tailgate is positioned responsive to the force of the wind or air pressure on the tailgate panel. This is done through the utilization of a dashpot type device in which a conventional door closure device is utilized to position the tailgate.
It will be appreciated in the above-mentioned patent that there is no attempt to counterbalance the tailgate during opening or, in fact, facilitate opening and closing of the tailgate. In this patent the spring tension is set to be responsive not to the weight of the tailgate but rather to the aerodynamic pressure on the tailgate which pressure exceeds counterbalancing forces. The reason is that not only must the weight of the tailgate be accommodated through the tensioning mechanism; it must counteract the force on the tailgate presented as a cross-section to the wind.
Wind pressures on a tailgate of 60xe2x80x3xc3x9720xe2x80x3 at 75 miles an hour exceed 150 pounds. On the other hand, the tailgate itself weighs, for instance, 50 pounds so that the tension set by the Durrell device would have to be three times that necessary for counterbalancing. The result is that with this device installed it would be virtually impossible to open the tailgate at all. As a result, the Durrell device must be disconnected in order to lower the tailgate. To this end, Durrell describes that its links can be quickly disassembled so that the tailgate can be lowered for loading of the truck. In short, although the Durrell reference utilizes a door closure apparatus for providing that the tailgate be partially opened in the presence of wind loading it does not aid in lowering and raising the tailgate to load or unload the truck.
In contradistinction to the above noted systems for controlling the lowering and raising of a tailgate, in the subject system a compact easily hidden and easily installed accessory provides a counterbalancing force for the tailgate that does not interfere with removal of the tailgate. The counterbalance force is set to be less than the weight of the tailgate at its lowest point so that once lowered, the tailgate remains down.
In one embodiment the counterbalance force is provided by a specially constructed spiral wound spring which although compact and hide able provides an unusual amount of counterbalance force. The spring is contained within an easily mounted module in a compartment to either side of the tailgate, between the tailgate and the sides of the truck bed. Although in spiral wound form, the spring pressure is sufficient to permit the counterbalancing of at least a portion of the weight of the tailgate. The spring permits controlled lowering of the tailgate at a safe rate as well as assisting lifting the tailgate by smaller, weak individuals, with the spring permitting a one-handed operation.
The spring in one embodiment is a 2xe2x80x3 diameter coil made of 4xc2xd wraps of 0.098xe2x80x3 thickxc3x970.500xe2x80x3 wide Type 1095 Carbon Steel which although compact provides 35 foot pounds of torque. The use of the spiral wound spring makes possible a small module that can be tucked away between the tailgate and the side of the truck bed where it is out of sight and unobtrusive.
In another embodiment, a concealed gas spring is used which when the tailgate is up is hidden between the tailgate and the truck bed side. The gas spring is set up so as to provide a counterbalance force that is insufficient to raise a lowered tailgate when fully lowered. The use of the gas spring has an additional advantage. Because of the damping action associated with the gas spring, its use for controlling tailgates means that even with handsoff, the tailgate will descend slowly. Thus once the tailgate is unlocked, even unattended, the tailgate will not come crashing down. Moreover, the top of the gas spring is offset for clearance for the usual safety strap that keeps the tailgate level when lowered. As an added advantage, concealment of the gas spring when the tailgate is up prevents contamination from loads hauled by the truck and general road debris.
The subject module is designed as an after-market package and can be bolted into place quite easily by non-professionals without drilling using the existing attachment bolts provided for the detachable folding straps and/or the tailgate hinge bracket on the tailgate side and the existing quick connect bolt on the truck side. The tailgate and the subject module can be easily lifted off the truck body without the use of tools by simply unclipping the detachable folding straps and the subject module from the quick connect bolts on the truck side. Its use is therefore attractive to suburban family members and non-professionals who are utilizing the pickup truck not only to haul light loads but also as a convenient family vehicle.
The subject system thus permits the lowering of the tailgate in a single handed operation due to the fact that the majority of the weight of the tailgate is counterbalanced by the restoring force of the spring. This precludes the necessity of utilizing either a person""s other hand to hold the tailgate or another portion of the person""s body.
Since tailgates are usually exposed to dust and dirt as well as mud and other grime, single-handed operation is useful so as to not soil one""s clothes when operating the tailgate. Additionally, the single-handed operation of the tailgate made possible through the subject invention eliminates the problem of strain on wrist ligaments and spraining of one""s wrist when unlocking the tailgate. Due to the tendency of one to use one""s knee to prevent the tailgate from falling, injury to one""s kneecap is avoided when using the subject invention.
Finally, injury to small children standing under the tailgate is eliminated due to the controlled lowering of the tailgate through the single-handed operation described above.
In another embodiment, a lost motion device is employed so that the tailgate can be cracked open freely; but is then maintained in a safe slightly open position by the use of a lost motion linkage in combination with a sufficient degree of pretension of the counterbalancing spring. One reason for the need for the lost motion device is that often the tailgate handle gets stuck due to road debris, mud or other contaminants which cause the tailgate handle to jam. In the process of pulling at the handle to free it, sometimes the tailgate is released suddenly and comes crashing down. The lost motion device permits an individual to yank at the handle to get it unstuck and yet keep the tailgate up until it is desired to lower it. In short, the lost motion device prevents free fall crash and provides a safety stop position no matter how the tailgate is opened.
The subject accessory thus provides safety to protect wrists, knees and small children. Its ease of use permits one-handed operation. The module is unobtrusive and does not protrude into the bed of the truck. Because of its design it promotes simple aftermarket installation with no drilling required and permits tailgate removal without the need to demount the module or use tools. Moreover when a lost motion linkage is employed it takes the worry out of opening the tailgate and any possible crash. Once the tailgate handle is lifted, the tailgate opens only partially and stays there even if the handle is let go. Thereafter the individual is free to lower the tailgate in a counterbalanced controlled fashion.
In summary, a compact one-handed tailgate accessory for assisting in the safe raising and lowering of tailgates includes a module tucked in-between the tailgate and the truck bed sides in a pocket so as to be hidden from view, in one embodiment having a spring loaded linkage which counterbalances the tailgate so that raising and lowering the tailgate can be accomplished with one hand, with the linkage sharing one or more common attachment points with the detachable holding straps of the tailgate to simplify installation of the module and facilitate removal of the tailgate together with the module and the holding straps from the truck body. The accessory provides the ability to lower or raise a tailgate by a small person or non-muscular individual such as a woman so that the bed of the truck can be easily and safely loaded or unloaded, the tailgate being maintained in the down position by its own weight. The tailgate attachment prevents wrist injury, knee injury and injury to any object or person below the tailgate when the tailgate is unlocked. Raising the tailgate is assisted by the spring loading. In one embodiment, a specialized spiral wound spring is used which is compact enough to fit in the cavity between the tailgate and the truck bed, yet strong enough to provide the counterbalance force. In another embodiment a pair of scissor links are utilized with spring loading at the joint where the scissors are pivoted to counterbalance the weight of the tailgate. In a further embodiment, a lost motion device permits free opening of the tailgate but then arrests it in a safe partially opened position to prevent free fall crash no matter how the tailgate is opened. In a still further embodiment, a gas spring is used to counterbalance the tailgate, with the end of the gas spring cylinder attached to the truck bed side offset to provide clearance in one embodiment.